Maria’s eye is 140 miles north-east of Barbados, and Maria is moving west-northwest at about 13mph.
The NHC says: “On the forecast track, the centre of Maria will move across the Leeward Islands late Monday and Monday night and then over the extreme north-eastern Caribbean Sea Tuesday and Tuesday night.”
The most southerly point of the Leeward Islands – where Maria will first strike – include Antigua and Barbuda. The latter island was evacuated after being devastated by Irma.
The NHC says that “a dangerous storm surge accompanied by large and destructive waves will raise water levels by as much as 5-7ft above normal tide levels near where the centre of Maria moves across the Leeward Islands”.
It also forecasts a maximum potential rainfall of 20in across the central and southern Leeward Islands – including Puerto Rico and the US and British Virgin Islands – through to Wednesday night.
“Rainfall on all of these islands could cause life-threatening flash floods and mudslides,” it warned.
Earlier this month, Hurricane Irma left more than two-thirds of homes on the Dutch side of the island of St Martin (known as Sint Maarten) uninhabitable, with no electricity, gas or drinking water.
The French government has said its side of St Martin – known as Saint-Martin – sustained about €1.2 billion ($1.44 billion) in damage, with nine deaths across Saint-Martin and nearby St Barts.
On the British Virgin Islands, entire neighborhoods were flattened.
After a visit to the area, British Foreign Secretary Boris Johnson described the damage as something “you see in images of from the First World War”.
Virgin boss Richard Branson, who has a home in the Virgin Islands, has been tweeting ahead of the storm’s predicted arrival, warning people to stay safe.
Hurricane Irma also hit the US, with 11 deaths being linked to the hurricane. Nearly 6.9 million homes were left without power in Florida, Georgia, North Carolina, South Carolina and Alabama.
A second hurricane, Jose, is also active in the Atlantic, with maximum sustained winds of 90mph.
The center of the storm was about 335 miles south-east of Cape Hatteras in North Carolina, the NHC said in its advisory on September 17.
Tropical storm watches have been issued for parts of the north-eastern US.
Tens of thousands of Louisiana residents have been ordered to evacuate as Tropical Storm Isaac picks up strength in the Gulf of Mexico.
Isaac may strike seven years to the day after Hurricane Katrina devastated the same area.
More than 50,000 residents of the St. Charles Parish in southeast Louisiana have been told to leave ahead of Isaac, which is currently churning in the Gulf.
Earlier in the day, Gov. Bobby Jindal had also suggested that anyone in low-lying parts of the state’s coastal parishes evacuate.
A hurricane warning has been issued for parts of the state east of Morgan City, which includes the New Orleans area.
Isaac is expected to be a strong Category 2 hurricane when it comes ashore late Tuesday or early Wednesday. Wednesday is the seventh anniversary of Katrina.
There were fears that Isaac could strike New Orleans with the same deadly force as the monster storm, which wiped out homes and led to the death of nearly 2,000 people.
Tens of thousands of Louisiana residents have been ordered to evacuate as Tropical Storm Isaac picks up strength in the Gulf of Mexico
Meanwhile, Isaac shifted West into the Gulf of Mexico after lashing the Florida Keys with strong winds and heavy rain.
Also on Sunday, Alabama joined Florida, Mississippi and Louisiana in declaring a state of emergency as Isaac looms.
The National Hurricane Center said Isaac was due to be at or near category-two hurricane strength soon after its center crosses the Florida Keys late on Sunday.
The latest forecast takes Isaac into the Mississippi coast with maximum sustained winds from 96 to 110 mph over the next few days.
At least 1,836 people died and cost of the damage was estimated at $110 billion. Forbes reported that Isaac has the possibility to rival Katrina in its destructive power.
A storm becomes a hurricane when sustained winds reach a minimum of 74 miles per hour (119 kph).
The NHC said Isaac was expected to intensify to a Category 2 hurricane, with “extremely dangerous” sustained winds of 105 miles per hour (169 kph), as it swept up the warm waters of the Gulf of Mexico.
The U.S. National Hurricane Center issued a hurricane warning for the northern Gulf Coast from Louisiana to the Florida Panhandle on Sunday.
At 2:00 p.m. (EDT) on Sunday, Isaac was about 50 miles (85 km) south-southeast of Key West and packing top sustained winds of 60 miles (100 km) per hour.
Tropical force winds from the massive storm stretched across 400 miles (644 km), with rain bands extending even further, said NHC meteorologist David Zelinsky.
It meant Isaac could cause significant damage even in places where it does not pass directly overhead.
“It certainly is a large storm,” he said, noting that wind gusts of 60 mph (100 kph) had been detected as far apart as Key West and Palm Beach.
The storm will likely pick up strength from the warm, open waters of the Gulf of Mexico and strike as a dangerous Category 2 hurricane somewhere between New Orleans and the Florida Panhandle on Wednesday.
Airlines cancelled hundreds of flights as the storm lashed southeastern Florida today. Airports in Miami and Fort Lauderdale were hit the hardest, cancelling 573 flights – the vast majority of the 654 U.S. flights grounded overall because of the storm as of Sunday morning.
There were scattered power outages from Key West to Fort Lauderdale affecting more than 6,000 customers, and flooding occurred in low-lying areas.
Isaac has brought havoc to the Caribbean already, killing seven people in Haiti and downing trees and power lines in Cuba.
It had officials worried enough in Tampa that they shuffled around some plans for the Republican National Convention.
Former Massachusetts Gov. Mitt Romney will officially be nominated as the Republican Party’s presidential candidate on Tuesday, one day later than originally planned.
His nationally-televised acceptance speech will be on Thursday night as originally planned.
Tuesday evening’s program includes remarks by Ann Romney, the candidate’s wife, as well as by New Jersey Gov Chris Christie, previously announced as the keynote speaker.
Paul Ryan will deliver his acceptance speech Wednesday evening in prime time in the eastern part of the United States, and Mitt Romney’s speech dominates the final night.